Mixer groups for bathroom or kitchen are known that allow an electronic adjustment of the flow rate and of the water temperature.
Such mixer groups comprise hot and cold water inlets, an outlet of mixed water, a pair of valves situated downstream of the respective inlets, motorised means for actuating the respective valves, electrically driven by an electronic card that is inserted in a hydraulically insulated seat of the mixer group itself. In particular, the adjustment of the flow rate is carried out through a keypad mounted, for example, on the sink plane or on the diffuser jet and electrically connected to the electronic card of the mixer group.
Such mixer groups make it possible to have an electronic control of the flow rate and of the temperature that is much more precise than a manual control and that are aesthetically more pleasing, due to the fact that they can adapt to upper end bathrooms and kitchens. Indeed, the control keypad can be left visible on the sink plane or it can be mounted on the diffuser jet, whereas the mixer group that carries out the adjustment of the water can be situated below the sink or in a hidden area.
However, the aforementioned mixer groups suffer from some limitations, mainly associated with their dimensions, and from some drawbacks relative to their maintenance requirements and to their operation.
As far as the dimensions are concerned, the coupling of the electric motors and of the valves is rather bulky, since that the electric motors are each equipped with their own rotation shaft fixedly attached to a corresponding gear which engages with a second gear mounted on a stem of the respective valve. In order to allow each electric motor to precisely adjust the opening of the relative valve, it is foreseen for there to be a transmission or reduction ratio between the gears, obtained by using a first gear for the electric motor and a second gear for the valve having a different diameter; such gears have a considerable bulk.
Moreover, in known mixer groups, seats are foreseen for receiving the valves that are in fluid communication with the inlets, to receive water. Such valves are big and contain discs made from ceramic for intercepting fluid, which are able to adjust the flow rate of the water according to the angular movement of their stem and have dimensions of about 3 cm diameter and a length of about 5 cm, including the length of the gear that projects from the body of the valve to be engaged by the gear of the electric motor.
Due to the aforementioned arrangement of the motors, of the valves, of the reduction gears and of the electronic card, as well as to the dimensions of the valves, of the motors and of the gears themselves, the mixer group is rather bulky and cannot always be inserted in the limited space available below the sink. Moreover, when the mixer group can be inserted, its installation substantially occupies a lot of the available space below the sink.
Of course, the mixer group can be installed in view, for example on the sink plane or at the edge of the tub, but in such a case it has an undesired bulk and, in any case, it is not very nice to look at.
On the other hand, it has been found that the gears of the motor and of the valves undergo wearing that tends to alter the adjustment precision of the mixer group, unless periodic and onerous maintenance operations are carried out that foresee extracting the mixer group from its housing, accessing the mechanical components, substantially removing a cover of the mixer group, cleaning and oiling the gears, as well as checking the correct position of the valves and the operation of the electric motors.
Finally, in known mixer groups, it has been verified that the electronic adjustment of the valves is rather noisy, due to the movement of the gears, and generates an annoying whistling noise, probably due to the flow of water inside the ceramic valves, which in some cases prevents it from being used in homes.
The problem forming the basis of at least some of the embodiments of the present invention is that of conceiving a mixer group for bathroom or kitchen with very small dimensions, suitable for being inserted in a small area beneath the sink or wash basin, without having an annoying bulk, whilst still being equipped with mechanical means for actuating the valves that are capable of adjusting the temperature and the flow rate in a particularly precise manner, without requiring substantial maintenance interventions over time and that is very silent. Another purpose of at least some of the embodiments of the invention is that of making it unnecessary to extract the mixer group once it has been installed, substantially overcoming the limitations and the drawbacks that still affect mixer groups according to the prior art.